(1) Field of the Invention
This invention relates to the removal of metal etch residue of silicon nodules resulting from a small percentage of silicon in the conductor metal. The residue is removed using ion beam bombardment.
(2) Description of the Related Art
A small percentage of silicon is often included in conductor layers to overcome device problems. During subsequent processing involving heating and cooling steps silicon can precipitate at metal grain boundaries forming silicon nodules. These silicon nodules etch differently than the metal conductor layer and lead to residue problems after the electrode pattern has been formed.
U.S. Pat. No. 5,175,125 to Wong discusses the silicon nodule problem, but uses method to solve the problem which are different from the method taught by the invention disclosed in this Application for Patent.
The use of boron trichloride, BCl.sub.3, as an etchant for aluminum is discussed in "SILICON PROCESSING FOR THE VLSI ERA--VOLUME 1, by S. Wolf and R. Tauber, published by Lattice Press, Sunset Beach, Calif. 1986, pages 559-564. The silicon nodule problem or methods to overcome this problem while etching aluminum are not discussed.